The devices and methods disclosed herein are for use in pH measuring and monitoring applications. There is a need in the art for ultrasensitive detection of pH in a rapid and reliable manner. Conventional pH sensors are generally confined by the Nernstian limit of 59 mV/pH, and have a detection limit practically constrained by signal-to-noise interference. Provided herein are devices and methods that vastly improve the pH detection limit by effectively increasing the Nernstian limit by an amplification factor. In this manner, a pH sensitivity that is better than 0.02 pH units is achieved, including as good as 0.002 pH units. Such an improvement represents about an order of magnitude improvement over commercial pH sensors.